The invention relates to a blood filter in medical devices.
It is known that in a very large number of medical devices there is a filter wherethrough blood passes during extracorporeal circulation from a patient.
Such filters have varied structural forms and dimensions so that they can operate throughout an entire range of blood flow from the minimum to the maximum flow rates. However, the filters of the prior art have several disadvantages.
One of these disadvantages is that when blood passes through the filter at the near-minimum flow-rate for which the filter has been dimensioned, the filter is filled by blood over a large percentage of its filtration medium surface, which is physiologically unfavorable.
A second disadvantage in near-minimum flow-rate conditions is the amount of time required for adequate hydraulic head pressure for the flow of blood through the filter.
Another disadvantage of known filters is the large internal volume which requires a high value of priming, i.e. of the amount of blood contained in the extracorporeal circuit.
An object of the present invention is therefore to provide a blood filter wherein the amount of filtration medium surface involved is optimally adjusted according to the flow-rate of the blood which passes through the filter, and wherein the optimum head is quickly obtained, even for low blood flow-rates.